The filibuster allows senators to hold up legislation without a 60-vote threshold.

Changing the floor rules to end the filibuster has been considered a “nuclear option” for lawmakers, as it could come back to bite the GOP if the Democrats were to retake the Senate.

In recent years, however, the party in control of the Senate has done away with other filibusters in an attempt to circumvent the opposition. Democrats eliminated the filibuster for executive and judicial nominees in 2013. And in April, Senate Majority Leader Mitch McConnell scrapped the filibuster for Supreme Court nominees to confirm Trump’s nominee, Neil Gorsuch.

The GOP is circumventing a possible filibuster for its healthcare bill by introducing it using a process known as budget reconciliation. As long as the bill cuts the federal deficit, it is not subject to a 60-vote threshold.

Both the GOP healthcare bill, the American Health Care Act, and Trump’s tax proposals have faced unanimous opposition from Democrats.

Trump’s suggestions followed a series of tweets Tuesday in which he criticized Germany and attacked reports on ties between his campaign and Russian officials.